Lava lamp, a novel peripheral Golgi protein, is required for Drosophila melanogaster cellularization

Drosophila cellularization and animal cell cytokinesis rely on the coordina ted functions of the microfilament and microtubule cytoskeletal systems. To identify new proteins involved in cellularization and cytokinesis, we have conducted a biochemical screen for microfilament/microtubule-associated pr oteins (MMAPs). 17 MMAPs were identified; seven have been previously implic ated in cellularization and/or cytokinesis, including KLP3A, Anillin, Septi ns, and Dynamin. We now show that a novel MMAP, Lava Lamp (Lva), is also re quired for cellularization. Lva is a coiled-coil protein and, unlike other proteins previously implicated in cellularization or cytokinesis, it is Gol gi associated. Our functional analysis shows that cellularization is dramat ically inhibited upon injecting anti-Lva antibodies (IgG and Fab) into embr yos. In addition, we show that brefeldin A, a potent inhibitor of membrane trafficking, also inhibits cellularization. Biochemical analysis demonstrat es that Lva physically interacts with the MMAPs Spectrin and CLIP190. We su ggest that Lva and Spectrin may form a Golgi-based scaffold that mediates t he interaction of Golgi bodies with microtubules and facilitates Golgi-deri ved membrane secretion required for the formation of furrows during cellula rization. Our results are consistent with the idea that animal eel cytokine sis depends on both actomyosin-based contraction and Golgi-derived membrane secretion.